1. Field
The invention concerns a fast-fit coupling for connecting appliances forming part of a medical or surgical handpiece system to a supply hose.
2. Description of Prior Art
Medical handpiece systems, consisting of a treatment instrument with a device for securing a treatment tool, a drive motor, any possibly required intermediate fittings and adapters, and a supply hose, have several interfaces which are bridged by means of couplings. Two types of couplings are currently in use for this purpose.
Various types of fast-fit couplings, e.g. plug-and-twist couplings, are used between medical appliances, e.g. a handpiece in the form of a treatment instrument and a motor. Such fast-fit couplings facilitate the rapid changing of handpieces during treatment and the removal of the handpiece for sterilization. In the main, these fast-fit couplings are in the form of spring-actuated (“non-positive”) plug connections, in which the transfer of various media, such as water and air, is effected via a coupling spigot, through the perimeter of which the media exit and then continue on their path through circular channels in the opposing fitting, which then enables the handpiece to be swivelled with respect to the motor. These couplings are especially suited to treatment instruments of small diameter but with a relatively large construction length, or to applications in which a large construction length is not disadvantageous.
The connection between the supply hose and the medical appliance, e.g. a motor, is usually detachable, but not of the fast-fit type, i.e. it is mostly achieved by means of a screwed union either with or without a coupling ring, or occasionally by means of bayonet lock fittings. Previously, fast-fit couplings were not required at this point since motors could not be sterilized and the handpiece therefore only needed to be detached in order to replace a damaged hose or to service the motor. However, on account of ever increasing hygiene demands and the technical improvements which make it possible to sterilize electric motors there now exists the urgent need to create, at the interface between the supply hose and medical appliance (e.g. a motor), an ergonomically advantageous, reasonably priced coupling which is fast and easy to handle for the user and simple to manufacture. In addition, this coupling should increase the assembled length of the system as little as possible.
Conversion systems, as is known from the FR 2.709.658 B1 for example, form part of the ‘state-of-the-art’ environment in the sector involving interfaces between a supply hose and a medical appliance, e.g. a handpiece or motor. In this case an intermediate coupling fitting is screwed onto the coupling-side end of the supply hose, and likewise onto the hose-side end of an instrument, these two intermediate fittings can then be coupled together by means of a bayonet lock fitting.
In U.S. Pat. No. 4,477,253, a coupling is described which possesses at least one flattened surface on a circular shaped segment and which fits into the opposing fitting on the hose side. The system is locked by turning the fixing by means of a pin.
The disadvantage of both these systems is that the handpiece has to be twisted with respect to the supply hose during the coupling or detaching process, a fact which makes the coupling and uncoupling process more difficult. Often the hose is at least partially twisted instead of the motor, a process through which the hose or parts thereof can become worn and break. In addition, locking the system can only be achieved through the twisting process. This means that, if not assembled properly, the motor and hose can become separated or that the system does not function correctly. In the case of conversion systems (FR 2.709.658) additional parts are necessary, a fact which increases costs, brings along more dirt-collecting edges in its wake, extends the system and increases weight.
In U.S. Pat. No. 4,403,959, a fast-fit coupling is described which is a plug-and-twist coupling. Locking is effected by means of ball bearings. The ball bearings are held in the recesses of a sleeve via another U-shaped, rotation-symmetrical, spring-loaded sleeve, until the sleeve is pushed back when the two parts of the coupling are pushed together and the ball bearings engage in recesses on the opposing fitting. When the coupling is detached an outer sleeve is pulled back and the ball bearings are once again released.
This plug coupling corresponds to those couplings which are usually used between medical appliances, such as a handpiece and a motor, for example. However, those couplings designed in the form of a twist coupling turn out to have a disadvantage at the interface between the motor and supply hose. Since all media transfer lines have to be contained in one coupling spigot, this therefore results in increased construction length and weight and the center of gravity of the whole handpiece system changes, thus making handling more difficult for the user.